University of Tehran Iranian Economic Review 1026-6542 15 29 2011 03 01 An Investigation Of Brain Drain From Iran To OECD Countries Based On Gravity Model 89 99 32724 10.22059/ier.2011.32724 EN Heshmatollah Asgari Journal Article 2013 05 19 https://ier.ut.ac.ir/article_32724_ea9656200183552508fbb3b74df2e94d.pdf